How to sync files between Windows and Ubuntu

I mostly use Dropbox to sync files between Mac, Ubuntu and Windows. I also use Ubuntu one sometimes. Ubuntu One is a free service that offers 2GB of storage on the cloud. Recently, Ubuntu one released the beta version for Windows that you can sync the files between your ubuntu and windows machine with your Ubuntu one account. It works on XP, Vista and Windows 7. Make sure you have the full .NET 4 framework installed.